PROTECTIVE EFFECT OF HEXETIDINE AGAINST IN-VITRO BACTERIAL DEMINERALIZATION OF BOVINE ENAMEL AND DENTIN IN THE PRESENCE OF FLUORIDE

Bovine enamel and dentin specimens were overlaid with acidogenic Strep tococcus mutans suspensions in agarose. In this model, the minimal dem ineralisation-inhibiting concentration (MDIC) of hexetidine was determ ined in the presence of fluoride. A commercially available mouthwash c ontaining 0.1% (2.9 mmol/l) hexetidine was diluted serially and added to the bacterial suspensions together with 0, 5.3, or 26.3 mu mol/l fl uoride (NaF). After 22 h of incubation at 37 degrees C the bacterial s uspensions were removed and assessed for calcium and lactate. The resu lts showed significant inhibitory effects of hexetidine on the deminer alisation of the enamel specimens with a MDIC between 15 and 31 mu mol /l hexetidine. In the presence of fluoride, approximately fourfold hig her concentrations of hexetidine were needed for a significant additio nal protection of the enamel. No synergistic effect between hexetidine and fluoride was observed. For the demineralisation of the dentin spe cimens, the MDIC of hexetidine had a value between 31 and 61 mu mol/l. At both these concentrations the dentin specimens were relatively les s protected in the presence than in the absence of fluoride, and some synergistic effect between hexeditine and fluoride was observed.